The invention belongs to the field of belt conveyors, and more specifically to belt conveyor rolls of the kind classified in U.S. Patent and Trademark Office Classification No. 198.
Conveyor rolls used in heavy industrial conveyors and in underground mining are lubricated infrequently and must operate for long periods of time with their own self-contained reservoir of grease and this must not be prematurely lost by leakage or centrifugal action.
These rolls are generally provided with grease fittings and they have a through passage of some kind from the grease fitting, through the bearing, and back to the outside so that during lubrication there is a visual indication that the bearing is filled.
In conventional rolls, it has been customary to have two kinds of seals, first, a labyrinthine arrangement of some kind which relies on a tortuous passageway to keep the lubricant in place; and second, because the labyrinth arrangements have not been completely effective, a rubber-like seal.
The rubber-like seals have two disadvantages. First, they are expensive. Second, they introduce frictional drag, often as much as one to four ounces hold-back at each roll surface. Where one troughing assembly uses three rolls and there is a troughing assembly every four to five feet for hundreds of feet, this creates a substantial overall drag and requires high horsepower inputs just to move the belt empty.
Preferably, a conveyor roll would be cheaper and better if these conventional rubber-like seals were eliminated.